Advanced Physics $-$ Electrostatic

Ex $2$

Protons are accelerated by a voltage of $9$ kV then directed towards an immobile target containing unknown atom nuclei. We observe that if a proton arrives exactly in front of one of these nuclei, it approaches it to a minimum distance of $\backslash (3\mathrm{.}2*10^\{-12\}\backslash$mathrm$\{$~m$\}\backslash ).$

a$)$ what is the initial speed of protons?

b$)$ Which atom are they nuclei?

c$)$ what speed would these same nuclei have if they were accelerated with the same voltage?

d$)$ what would then be the minimum distance if a nucleus were projected against another nucleus? Note$/$comment$?$

e$)$ how far would alpha particles arrive from gold nuclei?